


The Problem with Assumptions

by Sparcina



Series: Iron Webs to Covet [18]
Category: Doctor Who (2005), Spider-Man (Tom Holland Movies)
Genre: (Tony), Aged-Up Character(s), Alternate Universe - Canon Divergence, Anal Sex, Angst and Feels, BAMF Peter Parker, Casual Sex, Doctor who/MCU crossover, Jealousy, Kissing, M/M, Misunderstandings, Mutual Pining, Not Actually Unrequited Love, Post-Avengers: Endgame (Movie), Rimming, Rough Sex, So much pining going around, Tenderness, Unrequited Love, idiot in love
Language: English
Status: Completed
Published: 2020-11-09
Updated: 2020-11-09
Packaged: 2021-03-09 06:33:35
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 4,160
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/27466495
Author URL: https://archiveofourown.org/users/Sparcina/pseuds/Sparcina
Summary: The Doctor’s nice. Weird, but Tony likes weird, especially when it involves alien tech and casual trips in time. And then there’s all the sex, which helps take his mind off the one person he can’t have: Peter.Well, Tonyassumeshe can't have him.(He shouldn't make assumptions.)
Relationships: Peter Parker & Jack Harkness, Peter Parker/Tony Stark, Tenth Doctor/Jack Harkness, temporary Tenth Doctor/Tony Stark
Series: Iron Webs to Covet [18]
Series URL: https://archiveofourown.org/series/779883
Comments: 9
Kudos: 65
Collections: Flash With Benefits





	The Problem with Assumptions

**Author's Note:**

  * For [LearnedFoot](https://archiveofourown.org/users/LearnedFoot/gifts).



> LearnedFoot, I love and admire your writing. This is a gift for you - and a letter of appreciation ♥ ♥ ♥
> 
> Many thanks to the fabulous Lou for checking this fic over!
> 
> ***Main (and endgame) pairing: Peter/Tony***

Time travel was fun. Exhausting and dangerous, but hey, Tony had always liked to burn the candle at both ends. And when the candle was gone, well… He just kept going, because what was the purpose of life if not to unravel the mysteries of space and time with a guy he couldn’t stand, an alien who taught _him_ new tricks in the bedroom, and the one person he loved but couldn’t have?

All that time-hopping made for a great distraction. And so did sex with the Doctor. The sex was great, okay? Fighting off those Daleks wasn’t quite as fun, and Tony had almost lost an eyebrow to an _underwater fire_ once, but he wasn’t complaining. These vacations were overdue. And the fact that the accommodations were nothing like the inside of an actual telephone box was just a nice bonus.

He rolled onto his side, and watched the Doctor’s eyelids flutter open. They’d had sex an hour ago, and it wasn’t even their first round today. Well, ‘today’ was a very relative term around here, but Tony liked to keep track of time, and besides, he could tell by the ache. This was the good kind of ache, although he couldn’t quite recall when he’d last been fucked so much and so often.

(Outside of his fantasies, anyway. Fantasies he’d done his very best to wipe clean from his memory, but _feelings_ made it challenging.)

“So, what’s our next stop?” he reflected out loud, and wondered when his surprise ran out, exactly. After he discovered that his current fellow time-traveler/tinkering & fuck buddy wasn’t quite who he seemed, or that the telephone box wasn’t a telephone box at all? After he realized that interplanetary warfare and time travel were just a normal Thursday for the Doctor? Somewhere in between, when he figured out that he would have to call his bed partner by a self-appointed title because _baby_ and _sweetheart_ didn’t get him a positive reaction?

Strangely enough, _Your Lordship_ didn’t earn him any brownie points either.

“It’s your turn to choose, Tony.” The Doctor, who seemed to be running on an endless supply of candles, sat up in a frankly disturbing display of energy. “Where do you want to go next?”

Tony almost wiggled his eyebrows, but knew better than to go for a third round. Exploring some alien world sounded nice right about now. Even if he still, well, _ached_. He’d saved the universe (run for his life) under worse circumstances.

“Gimme one hour of shut-eye, and you can take us to that fun little place you mentioned yesterday.”

“Splendid! I’ll let the others know!”

The Doctor was already hunting down his clothes, and Tony admired the view. He’d never had a thing for pinstripes before, but then he’d met the Doctor.

“Sleep well, Tony,” the Doctor said.

Tony returned the smile with one of his own. Smiling was easy. Even when he didn’t mean it.

He buried his face in the pillow as soon as the door closed on the Doctor.

_I’ll let the others know._

“Fuck,” he grunted, and gave the mattress a half-hearted punch.

There _were_ aspects of these vacations he didn’t enjoy at all.

*

Jack Harkness was an easy-going, witty, handsome pansexual man who couldn’t die.

Tony hated him with a passion.

“I don’t hate him,” he assured Peter.

The kid didn’t appear convinced. In Peter’s defense, Tony had accidentally spilled his coffee on Harkness’s shirt today (for the third day in a row).

“You totally do.”

“Who does?”

“That’s joke getting old, you know.”

“Whatever you say.”

Peter kicked at a pink pebble the size of his foot. The alien rock hit the purple water several hundred feet away, bouncing five times before sinking in the ocean of their Planet of the Day. Tony, however, wasn’t interested in the color theme right now. Not with Peter at his side. So close. This particular temptation had always been close, and self-denial had never been Tony’s strong suit. Still, he kept his hands in his pockets, and pretended that he didn’t _need_ to touch. To card his hand through that mop of wild brown curls, so soft-looking. To pat his shoulder. A mentor-y squeeze, a friendly touch.

Yeah, right, who was he kidding.

“I like this planet,” Peter said, changing the subject with his well-known level of subtlety. “’s warm and smells sweet.”

“Smells sweet?” Tony asked, bewildered. _You smell sweet_ , he almost said, but he had years of practice keeping his mouth shut about such things. Because he was not a complete asshole.

Peter deserved better.

(Better than Harkness, that was for sure.)

“Hey, Jack!” Peter called out. Then, voice slightly hesitant: “Want to swim, Mr. Stark?”

“Nope.”

Of course, he wanted.

But Harkness was already there, frolicking in that ocean. And with Peter willing to join him, there was no room for Tony.

“Too bad.” Peter took off his shirt and ran towards the purple reef, laughing at something Harkness said that Tony couldn’t hear because he was just human and old and incredibly envious of the way that asshole caught Peter in his arms and spun him around. The kid’s laugh was full of unbridled joy, and Tony… Tony hated Harkness. And himself. That was one feeling he had in spades.

He spun around and started walking, hitting his own pebbles—much smaller—with the tip of his shoe. 

The scenery turned out to be very interesting after all.

*

It wasn’t that Tony didn’t want Peter to be happy. That was his one priority in life, higher up on the list than his own happiness. Which was probably for the best, because Tony wasn’t exactly happy these days. How could he, when Peter kept touching and laughing and _flirting_ with a handsome man who could time travel on a whim? Not that Tony wasn’t doing his fair share of flirting with his own time traveler, but that wasn’t the point.

“It’s obvious,” the Doctor said one night.

They were working on the TARDIS’s console. Or rather: the Doctor was tinkering with the command panel, and Tony was asking questions and handing out tools as asked.

“You love him.”

Tony dropped whatever passed for an Allen key around here. “I’m not.”

The Doctor crawled further under the console. “You are. Even Jack sees it.”

Tony had half a mind to yank on one of the delicate wires hanging loose, just to see the Doctor share at least some of his anger, but he was too respectful of a _sentient ship_ to cause it any harm.

“I hate you,” he groaned, and did the next best thing: he yanked the Doctor onto his lap.

They kissed for a while, Tony angry and demanding, the Doctor merely following his lead, gentle, always so gentle.

He was slightly less gentle about the clothes.

They fucked in the Doctor’s room, and for a little while at least, while the Doctor thrust into him, Tony got to forget about where that anger came from.

*

Tony didn’t stop hating Harkness, even after the infuriating Time Agent saved Peter’s life. He was entitled to his emotions. Even if they were unfair, or sucked.

*

The problem with assumptions was that they were often wrong.

Tony didn’t like to be wrong. But here it was, in the Doctor’s expression: that tender gleam in ancient eyes, the bitter twist of an all-too kissable mouth.

Yearning.

Tony saw it often enough in his own reflection to recognize it instantly. And if there was one thing he didn’t do (anymore), it was having meaningless sex with someone whose feelings didn’t match his own.

Tony didn’t love the Doctor. Maybe he would have, in another universe. Where Peter didn’t exist.

(Tony really didn’t want to consider a universe with no Peter in it. Peter _was_ his universe—he just didn’t know.)

“So, that was fun.”

“It was,” the Doctor agreed easily.

His smile reached his eyes, which was better than Tony could manage while surveying Peter and Harkness exchanging a parting hug. Fuck, life was unfair.

“Except for the part where that fool tagged along,” he mumbled.

The Doctor didn’t look surprised at the vehemence in his tone. “I can’t stand Jack either,” he assured Tony.

Tony doubted that their dislike for Harkness stemmed from the same place, but he didn’t feel like dissecting the statement. For one thing, Peter had gone from indulging in a never-ending ultra-intense hug to storming towards the Compound, and Tony really wanted to know what the hell was going on.

“Thanks for the ride,” he said, not quite sure how he meant that.

The Doctor nodded, as if he understood Tony better than he did himself—which was probably the case. There was no sadness in his eyes, only a strange melancholy that tugged at Tony like a magnet. For the first time since their chancy meeting near Titan, where the Doctor had un-gauntleted Thanos with that maddening screwdriver of his that could challenge physics but didn’t work on _wood_ , Tony got an impression of the Doctor’s true age. Of what it meant, to live too long. To be too old.

The realization hit a little too close to home.

A sad smile flashed on the Doctor’s lips. “Please don't do anything I would do, and don't do anything I wouldn't do. There's a little gray area in there, where you can find happiness.”

Exactly five seconds after the Doctor had departed and the only inkling of blue belonged to the sky, Tony realized where he’d heard those words before—and what it meant, that the Doctor could quote them back to him.

That bit about happiness, though: that wasn’t him.

(Didn’t mean it wasn’t _meant_ for him.)

He hurried after Peter.

*

“Hey.”

The gym was empty except for the lithe figure pummelling the Hulk-proof punching bag Tony had designed himself. Definitely _not_ Spidey-proof, it turned out.

Tony shelved the challenge for later.

“Hey, Pete, can we talk?”

“Can we _not_?”

Tony wondered if all that wibbly wobbly, timey wimey travel had addled his brain somehow, because Peter snarling at him, hands fisted and red in the face, like he was about to beat _him_ to a pulp, was one hell of a turn on. Which was unfortunate, because this conversation couldn’t be handled by his dick.

“Here.”

Tossing a water bottle at Peter, Tony sank down on the training mat. And winced. Which seemed to make Peter even angrier, for some reason.

“We didn’t have to leave so soon,” Peter mumbled, and sank into push-up position, one-handed.

Tony was absolutely _not_ drooling at the display of super strength. “Time travel is all good and well, but I’m sure a lot of people missed you here, on good old Earth. Your hot aunt must have been—”

“Don’t.”

“Don’t _what_? It was dangerous out there.”

“So was Titan, if I recall correctly, and you _planned_ that trip,” Peter snapped, not looking up, still breezing through his one-handed push-ups. “ _You_ were in danger.”

Tony shot to his feet, vibrating with the lingering terror from that day. “You were the one who jumped on Thanos’s back!”

“Only because you didn’t get there first,” Peter hissed back.

This wasn’t the first time they were having that particular argument, but the Doctor wasn’t there to act as referee right now. Tony felt a headache building beneath his temples and wished he dared walk up to Peter and shake him (kiss him) until the self-sacrificing, impossibly endearing and maddening young man stopped running head-first into danger ~~just like Tony~~.

He took a deep breath. “That’s not the point,” he said, and even though there was hurt flashing on Peter’s face, and he hated it, so much, he kept talking, because he’d never been able to control himself when he felt like that, and fuck, Peter had a gift to make him feel all wound-up and worried. “I’m responsible for you, not the other way around.”

Peter pushed himself into a crouch, and glared at him. “You’re the one who’s _fragile_.”

Tony blinked. Peter’s face crunched in an apological grimace. _Fuck_.

“Ouch,” Tony said, although not because he felt hurt. He didn’t. “Sure, I’m _just_ human. But that’s not what this is about.”

“Then what’s your point?”

That headache wasn’t going away anytime soon. “Your obsession with death, Pete.”

“You’re a hypocrite.”

Again, _ouch_. But Peter was right. _Again._ Didn’t mean that Tony couldn’t argue _ad nauseum_. He may be a genius, but he wasn’t irreplaceable. Peter was. Tony had almost lost him so many times already, and he knew he couldn’t deal with a world without him, couldn’t survive the emptiness left behind, the—

_No._

Tony watched Peter crushing the empty bottle in his fist, fingers itching for his own Voodoo doll. “It doesn’t matter if you’re mad at me,” he said, tone firm, and took a step forward. “If it means I can keep you safe—”

“Oh, is that so?” Peter dropped the bottle and stood in turn, nostrils flaring. “Last time I checked, you’re not my father.”

Tony went rigid, heart hammering painfully, the rush of blood in his ears almost deafening. If the kid had stood any closer… “Yeah, I’m not,” he growled, so many alternatives to those words pressing against his lips. “Or else you wouldn’t have spent so much quality time with that asshole.”

“Jack is _not_ the asshole here.”

“Not after he spent so much time fucking your ass, I bet.”

Tony wanted to take the words back as soon as they left his mouth, but Peter didn’t freeze, or react in any of the ways he usually did when Tony was a mean idiot. He… seemed to grow beyond the proportions allowed by his body, to feed on Tony’s rage.

“I have no idea why you assume I’m a bottom,” he said, with no blush, no hesitation whatsoever. “And since when are you even _thinking_ about my sexual life?

“That’s—” Tony floundered, and he never floundered. “I didn’t say—”

“You totally _said_ ,” Peter snapped. “And I don’t owe you any clarification, but I’ll have you know that I didn’t have sex on that spaceship, or on any of the world we visited, unlike you and the Doctor.”

Tony’s mouth was open, but no word was forthcoming. No justification. No explanation. Puzzle pieces he hadn’t even known were missing from the picture he’d had in his mind fell into place, their edges searing hot as their meaning dawned on him. He felt… like an idiot.

“You didn’t have sex with him.”

“But you had sex with _him_.”

“You didn’t have sex with Harkness,” Tony said again, as though Peter needed the extra clarification of a name. “I thought—”

Peter’s face was a study in mercilessness. For the first time in years, Tony found himself doubting his decision to stay away. What if Peter was _still_ not over him? What if he still liked Tony enough not to fall in bed with Harkness? Tony had seen how the guy looked at Peter. If Peter had _any_ interest in Tony, after all that time—

“You got it wrong. That’s the problem with assumptions.”

The cold rage in Peter’s voice hit Tony with the force of a freight train. _Damage-control._ That’s what he should be doing, before Peter ran away from him again—not provoking him further.

“I wasn’t trying to make you jealous,” he tried to explain.

Peter didn’t blink. “Then why _flaunt it_?”

“What?” Tony was an exhibitionist when the mood struck him, but he didn’t recall that happening on their trip. “I didn’t flaunt—”

“Not to a regular human, maybe, but you know about my senses. You think I didn’t hear you, _smell_ you, every time you had sex with him?”

“Smell…” Tony derailed the Implication Train before it could reach Main Station. _Fuck._ He’d certainly not been thinking about Peter’s heightened senses. Not consciously, anyway. Had he tried to make him jealous, or had he merely been that self-absorbed? Christ, both options were bad. He threw up his arms. “What do you want me to say here?” He was bad at this. He knew it. Pepper knew it. The tabloids couldn’t get enough of his fucks-up. _Fuck!_ “I didn’t mean to—God, Pete, I never want to hurt you, ever, but I can’t seem to—”

“How about you start with the truth?”

“What?”

Peter was suddenly very much into his space. Still angry, but the proximity granted Tony some measure of hope. If he could stop putting his foot in his mouth long enough to get it right…

“What do you want from me?”

Tony saw his own vulnerability mirrored in the kid’s eyes, and suddenly it was ridiculously easy to jump off that cliff.

“You,” he said, and for the first time in years, that tight knot in his guts loosened, making it easier to breathe. Chris, he’d never expected a _confession_ to grant him such relief. “I’ve wanted you for a long time, but it wasn’t… It took me some time to accept that—”

“Because I’m me.”

The self-deprecation lacing the words broke Tony’s heart. “No.” He gripped Peter’s shoulders before he could talk himself out of it. Didn’t shake, didn’t pull, but _held_. “I didn’t say anything because I’m _me_ , sweetheart.”

“You don’t get to call me any pet names.”

Tony’s heart sank. “Sorry. That’s—”

“Not until you kiss me, I mean.”

So Tony kissed him. And Peter, _fuck_ , he kissed him back with such raw determination that Tony wondered why exactly he’d _assumed_ that the kid would be a shy lover. There was nothing hesitant about the way Peter licked into his mouth or sucked on his tongue. When Peter nipped at his bottom lip with a groan, he almost drew blood.

“Fuck,” Tony gasped when Peter started on his neck, sucking at the skin just over his pulse point. “You’re—Jesus, I can’t believe I was so stupid.”

“I can,” Peter said, but the tender way he kissed the bite mark at his throat took the sting off the words. “I was so obvious, Tony. Still am. Even on the TARDIS. Actually, especially on that fucking ship.”

“I thought you liked the— _ah_ —ship.”

Peter was fondling him through his pants, and Tony distinctly felt like a teenager about to cream his pants.

(He’d never done that, even as a teenager.)

“I liked the ship.” Peter’s voice dropped in pitch as he pressed his own erection into Tony’s hip. “And the Doctor too, until you started sleeping with him.”

“Better me than you. Chris, Pete, that’s—”

“Jealous much?”

“Possessive,” Tony choked. 

That earned him a full-body shiver from Peter, and wasn’t that interesting? But first things first. “Pete.”

“Uh?”

Tony tugged at the hand on his groin. “Stop a second.”

Peter froze. “Something wrong?”

“No, sweetheart.” Tony tried to smile despite the sudden tightening of his chest. That cliff was far higher than he’d expected, but free falls was part of his day job, wasn’t it? “I just want to make sure we’re both on the same page.” He brought their hands to his lips and kissed Peter’s knuckles. “Since I’m making too many assumptions, I’d just like to state that while I’d enjoy having you in my bed, or anywhere else, really, I’ll try to find the will to say no if this is a one-time thing. I want you like crazy, Pete, but I can’t do casual… not with you. And I get that you’re young and want to keep your options open—”

“You’re making assumptions again,” Peter said, the note of chiding in his voice not quite strong enough to hide the affection. “I _love_ you.” Peter freed his hand and cradled Tony’s face with both hands, eyes alit with all the stars Tony ever cared to see. “You’re the only want I want, okay?”

Tony couldn’t come up with any more words, but somehow, that was all right.

*

They made love right here in the gym, because neither of them had the patience to wait. Thankfully, the training mats were the comfy kind, and Tony didn’t mind spending the whole evening on his back. He barely felt the pain in his joints, but that may be Peter’s doing—the kid was wickedly good with his tongue, and Tony did _not_ want to know how he acquired that particular skillset.

“Kiss me again,” he rasped, ever greedy.

And Peter, ever indulging, leaned down to do precisely that, his thrusts steady and deep. For all that Peter had torn their clothes earlier, he’d spent _ages_ opening him up afterwards, as though Tony wasn’t still stretched aplenty from all his sex with the Doctor. Actually, _that_ may explain why Peter had done it—a punishment wrapped up in a bout of possessiveness. Tony had zero problem with Peter licking away the taste of a former bedmate. _Or_ being fingered open until he thought he’d go crazy with want. The hunger etched on Peter’s face while he massaged his prostate was well-worth the bout of madness.

“H-Harder.”

“I don’t want to hurt you in a way you wouldn’t enjoy,” Peter said, and okay, Tony needed a couple of seconds there to process all the _implications_.

“Come on,” he said at last, hips bucking. “Pete, please—”

Peter flipped him over and started pounding into him without further ado. Tony fisted his hands in the sheets and moaned. Pain sizzled through his pleasure on the third trust, and he just. Wanted. More. He could feel Peter’s hot breath against his nape, and then his teeth, sinking into his skin, the sting of the bite a perfect counterpoint to the deep ache building up in his ass.

“ _Tony_.”

Tony still hadn’t come when Peter spilled inside him for the third time. There was _no_ way he was going to fall prey to his own biological imperatives while the kid still had that kind of energy to spare, and besides, he’d often fantasized about Peter fucking him while he was drifting off, blissed out of his mind.

“There’s… a plug in the drawer,” he informed him, dizzy and weary and _hurt_ in the very best way.

Peter’s only answer was to crawl down Tony’s body and shove his tongue up his ass, stopping his own come from leaking out.

“That… also works.” Tony could feel that tongue thrusting in and out of him, a wet, warm caress that made his toes curl. When his orgasm tore through him, he didn’t make a single noise.

Peter’s rhythm didn’t falter, his tongue an intense caress that skirted the edge of _toogoodtoomuch._ “Fuck.” He gave a full-throated moan, and felt a spasm go through his right leg. Peter’s hand tightened on the matching asscheeks. “You’re insatiable, baby.”

“Want me to stop?”

Only if Tony could kiss him instead.

*

The bath was nice. Tony couldn’t recall why he took so many showers when he could chill in a Jacuzzi instead. It was probably Peter’s influence. Peter, who had his arms wrapped around him, and his chin hooked on his shoulder. Tony could hear his heart beat almost in sync with his own.

“I’m so lucky.”

“Yep,” Peter agreed, and nipped at his earlobe. “You are.”

“A lucky idiot.”

“ _My_ idiot.”

“Your idiot.”

*

“That went well.”

The Doctor almost dropped his screwdriver. “Jack,” he scowled, bristling at the interruption. “When will you stop doing that?”

“That’s a tricky question, from a Time Lord.”

“Go away.”

“Why?” Jack shrugged off from his coat and draped it on the one seat the Doctor kept insisting was _his_. “Because moping is such a stellar activity? Come here.”

“Don’t—Jack!”

Jack only tightened his embrace while the Doctor gripped his arms and tried to push him away. “I know I don’t feel right to you, but you acting like this doesn’t sit right with _me_.”

The Doctor slumped back into Jack’s torso with a weary sigh. “It’s hardly your fault I always allow myself to fall for those who aren’t meant for me.”

“We both knew that Tony wasn’t available. I mean, the way he was looking at Peter, and the way Peter made it a point to touch me as much as he did to rile him up… not that I’m complaining, but… A blind man could see that those two are meant for each other.”

“I don’t believe there’s anyone out there for me.” The Doctor huffed. “I’m too old to get heartbroken.”

“Then make it easier on yourself.”

“What’s that supposed to mean?”

Jack cupped his chin and turned his head around, slow but confident. He’d always been daring like that. “I may not feel right, time-wise, but I could make you feel good for a while. If you wanted.”

“I don’t—It’s not fair for you.”

“Do I look like I mind being the temporary rebound you obviously need?”

“I don’t need anything!” the Doctor snapped.

“Then tell me to stop.”

Jack kissed him.

The Doctor didn’t stop him.

**The End**


End file.
